1. Field of the Invention
This invention relates to batching items, e.g., based on weight or other characteristics of the items. The batching of items is sometimes referred to as "the on-line bin-packing problem." More specifically, this invention relates to the problem of accumulation of non-uniform items forming a best possible uniformity of the accumulated batch.
2. Background
In various industries, basic items are sold in batches satisfying various constraints. For example, many food items (such as, e.g., fresh or frozen fish portions, chicken portions and the like) are sold in prepackaged batches having a predetermined weight and/or number of pieces, within given tolerances. The tolerances may be quite strict in some industries.
Batching has developed as a result of contracts between sellers and purchasers for delivery of products which must satisfy minimum weight or other requirements. It is very important that none of the collections be below minimum weight but exceeding this weight results in an economical loss for the manufacturer, has impact on the transportation costs, taxation fees etc.
Various statistical methods have been suggested for solving the problem of reaching the batch size with as little overweight as possible. E.g., some prior art teaches the use of equations for a normal distribution or similar use of algorithms based on weight distributions. Such methods have disadvantages in that they are often difficult to apply, use large amounts of computer memory and use large computer processing resources each time an item is to be assigned to a batch.
One way to overcome the difficulties with these known methods is to omit updating all sets of data when an item is assigned to a batch. However, a major drawback of omitting updating of the sets of data is that changes in the population of items are not captured by these methods and these methods may then be based on wrong, or at least inaccurate, statistical data, whereby the batching by these methods will be less optimal.
The omission of data may have a large influence on the batching process where, for instance, the distribution of items which initially follows a normal distribution then changes and follows another distribution. Such a situation may occur if items having a special characteristic temporarily are assigned to special processing.